SCIENCE AND PRACTICE. 327 



IX. In cyanide of potassium 1 part, water 6 parts. 



17. Zinc Silver 0*545 



Silver Iron 0-420 



Zinc Iron 0'967 



18. Zinc Copper 0'052 



Copper Bismuth 0-818 



Zinc Bismuth 0'874 



B. Two metals and two fluids. 



a) Iron in diluted sulphuric acid 1 part acid, and 



49 parts water ^0*461 



Copper in concentrated solution of sulphate of 

 copper 



b) Copper in concentrated solution of sulphate of \ 



copper ! 0*711 



Platinum in nitric acid (sp. gr. 1'34) ) 



c) Iron in sulphuric acid ....... } 



Platinum in nitric acid j 



The following determinations were made by the same 

 physicist with Ohm's method : 



I. GEOVE'S ELEMENT. 



Zinc in diluted Sulphuric acid (1 : 4) ; Platinum in nitric acid (fuming) =1-8 12 



Ditto (1: 4); Ditto (sp. gr. 1-33) =1-678 



Ditto (1:12); Ditto ( ditto 1-33)= -603 



Ditto (1: 4); Ditto ( ditto 1-19) = -558 



Ditto (1 : 12) ; Ditto ( ditto M9) = -512 



Zinc in sulphate of zinc solution ; Ditto ( ditto 1-33) = 1-550 



Zinc in solution of common salt ; Ditto ( ditto l - 33)= -765 



II. DANIELL'S ELEMEXT. 



Zinc in sulphuric acid, diluted (1 : 4) ; Copper insulphate copper solution I'OOO 

 Ditto (1:12); Ditto 0-906 



Ditto ( 1 : 12); Copper in nitrate of copper solution 0'926 



The foregoing are a few of the numerous valuable com- 

 parisons with which Professor Poggendorff has enriched the 

 science of galvanic electricity. Others of equal value have 

 been made by Joule, Wheatstone, Svanberg, and various 

 other physicists. They all agree pretty well amongst each 

 other, considering that different methods were employed in 

 the comparisons. As an instance, the electro -motive force 



